Adjustably tuned coupling unit



April 1950 w. w. DEWHURST EIAL 2,503,100

ADJUSTABLY TUNED COUPLING UNIT Filed Aug. 24, 1945 2 Sheets-Sheet 1 INVENTORS nan/c: w .DA'Wf/UAEST & /uw. .BF/V/YFTT ail h ATTORNEY April 1950 w. w. DEWHURST ETAL. 2,503,100

ADJUSTABLY VTUNED COUPLING- UNIT 2 Sheets-Sheet 2 Filed Aug. 24, 1945 mmlllllll INVENTORS 14444146? 144 .DA-W/VU 7' 641/1 Eff/Y/YETT ATTORNEY Patented Apr. 4, 1950 ADJ USTABLY TUNED COUPLING UNIT Wallace W. Dewhurst, Haddon Heights, and Paul R. Bennett, Merchantville, N. J assignors to Radio Corporation of America, a corporation of Delaware Application August 24, 1945, Serial No. 612,504

6 Claims.

This invention relates to improvements in adjustably tuned coupling units for use in superheterodyne and other multi-stage radio receivers. Modern radio receiving sets are capable of translating not only broadcast frequencies but also frequencies within the low, intermediate, high and ultra-high frequency ranges, usually five bands in all. Such multi-band receivers may require fifteen or more adjustably tuned coupling units in the antenna, oscillator and other high frequency stages and, obviously, the mounting and the electrical alignment of these numerous units are major problems in the mass production of multi-band receivers.

Accordingly, the principal object of the present invention is to provide an improved adjustably tuned coupling unit, or bank of such units, and one characterized by its ease of assembly, the accessibility of its tuning control elements, and by its rugged yet inexpensive and compact construction.

The foregoing and other objects are achieved in accordance with the invention by the provision of an adjustable inductance-type tuner wherein the inductor, the trimmer capacitor and the separate adjusting members for the said parts are arranged in a novel manner along a common axis and supported upon a bracket for attachment as a unit to the base or to a panel of a radio chassis.

In the accompanying drawings:

Fig. l is an enlarged elevational view of a bank of two adjustably tuned coupling units constructed and mounted in accordance with the invention,

Fig. 2 i a sectional view taken on the line 2-2 Of Fig. 1,

Fig. 3 is a plan view of another embodiment of the invention,

bracket plate bent into approximate U shape,

thus having a bracket base or intermediate perforated fiat mounting length with two securing arms the ends of which are bifurcated or of other deformable shape, as indicated at l a, to facilitate its attachment to securing openings in the base or to the front panel 30f a flat radio chassis portion. The base or panel 3 is provided with a large central aperture 3a, through which access may be had to the intermediate U portion of the bracket, and with two mounting holes in which the tongues la are locked byspreading them apart, preferably. laterally, or by other deformation after insertion as shown in Fig. 2.

The bracket l constitutes a support for anchoring through the perforations one or more tuning "units'comprising a-tu'ning assembly including adjustable reactance means such as an inductance coil 5 and an elemental movable adjustment operating element such as the trimmer capacitor I mounted on opposite ides of the flat mounting length. The coil 5 of each unit is wound upon a hollow cylindrical insulating form or tube 9 and is supported by an internally threaded collar H which is staked or anchored by a tubular clamping member II to the base of the bracket, as indicated at Ha, Fig. 2. Each coil 5 is provided with an inductance-varying magnetic core I3 which is mounted for movement within the coil form 9. An adjusting screw 15 for the core is threaded through the collar l I which registers with and passes through the bore of a rotatable sleeve 1'": or passageway in the trimmer capacitor l to a point which is accessible from the front of the apertured base or panel 3.

Referring still to the embodiment of the invention shown in Figs. 1 and 2 the elemental capacitor 1 comprises an inverted cup-shape base l9 which is fixed to the bracket I as by one or more rivets 2i (Fig. 2), and a revolvable disc or top plate 23 which is fixed on the rotatable hollow metal'sleeve H. The shell is and the disc 23 are preferably constituted of a ceramic insulating material and comprise discrete supports for two metal electrodes, 25 and '21 respectively. The fixed electrode, 25, comprises an adherent film-like deposit of silver, or the like, which covers a part of the top urface or base of the shell 19 and is connected to a terminal 29 through the rivet 2| as by a spot of solder 3|. The adjustable armature 2! comprises a similar complementary metallic layer on the exposed or top I surface ofthe rotatable disc 23. This latter metal layer 21 is connected as by means of a soldered lead 33 to the rotatable metal sleeve I 7 upon which the disc 23 is fixed. The sleeve ll, in turn, is connected by means of a spider or other biased contact 35 to a terminal .lug 35a which extends through a suitable aperture or slot Isa to the exterior of the shell l9. As indicated in the drawing the opposite ends of the coil 5 are connected to the capacitor electrodes 25 and 21 through the terminals 29 and 35a respectively.

It will be observed upon inspection of Fig. 1 that the exposed or leading end of the sleeve ll, through which the core-adjusting screw l5 passes, is in the form of a hexagonal nut Ila, and that this nut and hence the capacitor electrode 21 which is affixed thereto, are accessible for adlustment (as by means of a suitable tool, not shown) from substantially the same point at the front or top of the panel 3 as is the core adjusting screw I5. One very real advantage of this arrangement, as compared to present day arrangements wherein the coils and trimmer capacitor are mounted in separate banks, is that there is no possibility of misunderstanding: as

to which capacitor is associated with a given coil assembly. Furthermore, it is'apparent that this coaxial arrangement of the separately adjustable elements and Ila provides a tuned coupling unit which, by reason of its compactness and ease of adjustment, is peculiarly suited for use in multi-band radio and television receivers.

In the embodiment of the invention'shown in Figs. 3, 4 and 5 the ceramic base-'for-the trimmer capacitor is in the form of a slab, here designated 4|, and is attached to the bracket 1 by spinningover the lower end of an internally-threaded sleeve 43 which accommodates a complementary threaded core-adjusting screw 45. This spunover end 430. (see Fig. 4) of the sleeve 43 also serves to ailix'the collar 41, which supports the coil form 9, to the bracket l. "l "in this case comprises two thin metal plates 5| and 53 which are attached to the slab 4| by rivets 55 and 57 respectively, and an interposed sheet 59 of mica or other dielectric material.

The capacitor As shown more clearly in Figs. 3 and 5 the upper electrode 5| comprises a flexible-metal strip which is bent around the ceramic insulator 4| and secured to the underside thereof by the rivet 55.

The free-end of this flexible strip 5| extends across the mica insert 59 and is biased away from the said insert into contact with a washer 6| about the sleeve 4'3. A nut 63 in this case is mounted on the threaded outer surface of the' sleeve 43 and operates to alter the capacitance of the device by changing the effective spacing between the flexible plate 5| and the fixed lower plate 53. When, as in the instant case, the electrode 5| (or 53) comprises a'very thin metals;

strip, its terminal 53a (see Figs.3 and 5) may be reinforced by the provision of an auxiliary terminal 531) which is mounted in register with the main terminal 530. and affixed to the base 4| by the same rivet 51.

As in the previously described embodiment of the invention, the several parts (43, 5|, 53, and 59) of the elemental capacitor 1 have centrally I aligned apertures through'which the core ad- Thus, both the capacitor i and the core I3 are accessible for adjusting screw 45 extends.

justment from the front or top of the panel 3.

It will now be apparent that the presentinvention provides an improved adjustably tuned coupling unit or bank of units, and one characterized by its ease of assembly, the accessibil- 'ity of its tuning control elements, and by its rugged yet inexpensive and compact construcin approximately the same direction at each end' of the mounting length to form the arms of the U; a tuning assembly including adjustable re- 'actance means anchored through the perforations on the mounting length; said adjustable reactance means having movable adjustment operating elements all of which are positioned for operation from the side of the mounting length in which the securing arms extend; and said securing arms having readily deformable free ends shaped for insertion in securing openings of the fiat chassis portion and for deformation after insertion, to anchor the unit in place.

"adjustable inductor including a coil held on a tube secured adjacent one end by a tubular clamping member anchored in a perforation in the mounting length, and an inductance varying core axially adjustable in position with respect to the coil by manipulation via the hollow interior of said tubular clamping member; and said adjustable capacitor having a passageway and being positioned with this passageway "in register with the hollow interior of the tubular clamping member.

3. The combination as defined -by claim 1 in which the bracket plate is metallic; and the free ends or the securing arms are of reduced width to provide a positioning shoulder, and are split to increase their deformability.

4. The combination asdefined by claim 2 in which the adjustable reactance means includes a plurality of different separately adjustable, capacitors and a plurality of different separately adjustable inductors.

5. In an adjustable tuning unit for securing to a flat wall portion of alternating current electric circuit apparatus and connection with the circuit to provide the desired tuning: an elongated perforated mounting bracket plate; a tuning assembly having at least one adjustablecapacitor member and atleast one adjustable inductor member held on opposite faces of a perforated portion of the plate, all said members being adjustable from one side of the plate; said adjustable inductorincluding a coil held on a tube secured at one end by a tubular clamping member anchored in a mounting plate perforation, and an inductance-varying magnetic core axially adjustable in position with respect to the coil by manipulation via the hollow interior of said tubular clamping member; and said adjustable capacitor member having a passageway and being positioned with this passageway in registerwiththe hollow interior of the tubular clamping member.

6. The combination as defined by claim5 in which the tubular clamping member penetrates the passageway, engages a portion .of the capacitor member facing away from the plate, and clamps the parts of the unit together.

WALLACE W. DEWHURST. PAUL .R. BENNETT.

REFERENCES CITED The following references are of record in'the file of this patent:

UNITED STATES PATENTS Number Name Date 1,935,354 ,Dressel Nov. 14,1933 2,035,439 'Crossley Mar. 24,1936 2,130,815 ,Riepka Sept.20,.l938 2,135,841 Polydorofi .Nov. .8, 1938 2,176,064 Cole .Oct. 17, 1939 2,180,413 Harvey Nov.i21, 1939 2,222,770 Hartl Nov. 26, 1940 2,291,787 Beanland -Aug. 4, v.1942

FOREIGN PATENTS Number Country Date 444,013 Great Britain Mar. 5,..1936 

